The treatment of water to kill biological contaminants, such as algae, bacteria, viruses, and the like, and to coagulate and remove these pollutants, as well as non-biological particulates, contaminant metals, and the like, and in particular, to disinfect water for drinking or to "decontaminate" water for safe environmental discharge, has a long history. Nonetheless, the practice of water treatment continues to evolve as new discoveries are made.
Typical prior practices comprise addition of chlorine to the water stream, to kill bacteria, algae, viruses, and the like, along with addition of anionic or cationic polymeric coagulants. Electrostatic interaction between the contaminants and the coagulants tends to coagulate the contaminants into particles large enough to be removed by filtration or settling.
As of the filing of this application, it appears very likely that the practice of chemical chlorination, long the preferred method of disinfecting drinking, industrial, and swimming pool water streams and the like, will be banned or severely restricted within the next few years.
Accordingly, a substantial need exists for methods of removing contaminants from water avoiding chlorine or other chemicals thought to be toxic. More specifically, a need exists for methods of water treatment and disinfection not involving introduction of chlorine or additional toxic chemical treatment substances into the water stream.
Preferably, any water treatment method replacing chlorination and other chemical treatment would be economically practiced, and apparatus for its practice would be available as a unit for retrofitting systems now employing chlorination and chemical treatment, such as swimming pool disinfecting systems, drinking water processing plants, and/or industrial wastewater treatment systems. In this connection, while the present invention is described herein primarily as a replacement for chlorination and chemical treatment in connection with swimming pool, drinking water, and/or industrial water streams, and the like, the present invention may find application in many other water streams where purification and disinfection must be accomplished without chemical coagulant treatments.
The present inventor has been working in the field of purification of contaminated water systems without employment of chlorine and chemical treatments or the like for some years. See U.S. Pat. No. 4,563,286 and 4,655,933 to the present inventor and Scott J. Johnson. These patents both recognize that a water stream can be purified by introduction of ionized oxygen tending to oxidize various pollutants, and teach further that ionized oxygen can be produced by exposing atmospheric air to ultraviolet light, particularly in the presence of permanent magnets.
U.S. Pat. No. 4,562,014 to the inventor herein discloses a system for introducing oxidant gases such as ionized oxygen into a water stream. A venturi is employed for dispersing the gas in the liquid stream; thorough mixing of the gas and liquid streams is encouraged by the drop in pressure after the venturi. The teachings of this patent are employed in the present invention, as will be apparent from the discussion below.
U.S. Pat. No. 4,382,866, also to the present inventor, shows a system for performing electrochemical filtration to remove flocculated or coagulated pollutants from a contaminated water stream.
Copending U.S. patent application Ser. No. 08/200,749 in the name of the present inventor and another discloses further improvements in the removal of contaminants from water streams by encouraging flocculation thereof, such that physical separation is then possible. The teachings of copending Ser. No. 08/200,749 may be employed together with the teachings of the present invention, where the nature of the contaminated water stream indicates that both techniques may be of use.